Rotary diaphragm pump

ABSTRACT

The rotary diaphragm pump has a flexible, resilient diaphragm band surrounding an elliptical frame within a case having four chambers surrounding an elliptical core. An articulating mechanism has a plurality of wheels traveling along the elliptical edges of the frame. The mechanism extends and retracts as the wheels move from maximum extension along the major axis of their elliptical tracks to minimum extension at the minor axis of their tracks. This mechanism drives a pair of actuator rollers along the inner surface of the diaphragm, periodically forcing the diaphragm into the surrounding chambers to produce the pumping action. Each chamber has an inlet port and an outlet port. The various ports may be interconnected to provide one or more multi-stage pumps in combination with one or more single-stage pumps, as desired. Two or more pumps may be joined in tandem to provide greater capacity from a single drive shaft.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to fluid transfer devices, andparticularly to a rotary diaphragm pump having an elliptical banddiaphragm driven by an articulating roller assembly.

2. Description of the Related Art

Fluid transfer devices, e.g., pumps, often use the principle of adistensible elastomeric diaphragm as the primary component therein.Various mechanisms are used to move the diaphragm and thereby change thevolume of one or more chambers within the pump in order to move a fluid(air or liquid) through the pump. The diaphragm in such a pump generallyhas a flat, planar configuration when it is not distended by the drivemechanism. The diaphragm in such a pump configuration is secured aboutits periphery, and the drive mechanism generally is secured to thecentral area of the diaphragm. The stress imposed upon the diaphragm bybeing mechanically attached to other structure both about its peripheryand its central area results in relatively large stress upon thediaphragm and correspondingly shortened life. Various hydraulicallyactuated diaphragm pumps have been developed in an effort to reduce thestress on the diaphragm, but such hydraulically actuated pumps generallysuffer from reduced mechanical efficiency in comparison to mechanicallyactuated planar diaphragm pumps.

Another disadvantage of such conventional diaphragm pumps is that asingle diaphragm generally corresponds to a single pump chamber. Theefficiency and smoothness of operation of the pump is thus relativelylimited in a manner somewhat analogous to a single cylinderreciprocating pump or engine, so that it has only one power stroke orpulse per revolution. In many applications, relatively smooth output ofthe pump, i.e., avoiding significant variations in output pressureduring each revolution of the pump drive, is a very desirable feature.Conventional mechanically driven planar diaphragm pumps are incapable ofproviding such smooth fluid delivery unless equipped with additionalcomponents to smooth the pulses delivered from the pump.

Thus, a rotary diaphragm pump solving the aforementioned problems isdesired.

SUMMARY OF THE INVENTION

The rotary diaphragm pump has a flexible, resilient diaphragm in theform of a closed band having an elliptical form when installed over anelliptical frame. The diaphragm band and frame assembly are installed ina case having four chambers surrounding the elliptical diaphragm andframe. An articulating mechanism is disposed in the center of the caseand diaphragm. The articulating mechanism has drive wheels rolling alongone or both of the elliptical inner edges of the diaphragm frame. Thearticulation of the mechanism as the wheels move from their maximumextension along the major axis of their elliptical tracks to theirminimum extension at the minor axis of their tracks causes a pair ofmutually opposed diaphragm rollers to bear against the inner surface ofthe diaphragm and alter the volumes of the four surrounding chambersaccordingly to produce a pumping action.

Each of the four chambers has an inlet port and an outlet port. Thevarious ports may be interconnected in various manners to provide eitherfour single-stage pumps; two two-stage pumps; two single-stage pumps andone two-stage pump; a single-stage pump and a three-stage pump; or onefour-stage pump, as desired. Optionally, two or more cases may be joinedin tandem to provide greater pumping capacity from a single driveshaft.

These and other features of the present invention will become readilyapparent upon further review of the following specification anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a rotary diaphragm pumpaccording to the present invention, one of the housing plates beingbroken away and partially in section to show details thereof.

FIG. 2 is a perspective view in section of the rotary diaphragm pump ofFIG. 1, shown assembled and illustrating its internal configuration.

FIG. 3 is a schematic geometric diagram of the outline of the internalvolume of the case of the rotary diaphragm pump of FIG. 1, showing theelliptical path of the cam and followers superimposed thereon.

FIGS. 4A, 4B, 4C, 4D, 4E, 4F, and 4G are front views in section showingthe sequential action of the pump mechanism of the rotary diaphragm pumpof FIG. 1 within the case and the deflection of the diaphragm by therollers of the mechanism to provide the pumping action.

FIGS. 5A, 5B, 5C, 5D and 5E are front views in section illustratingdifferent combinations of inlet and outlet paths made possible by therotary diaphragm pump of FIG. 1.

FIG. 6A is a perspective view of a first embodiment of a link bar usedto form the articulating mechanism of a rotary diaphragm pump accordingto the present invention.

FIG. 6B is a perspective view of an alternative embodiment of a link barused to form the articulating mechanism of a rotary diaphragm pumpaccording to the present invention.

FIG. 6C is a side view of the articulating mechanism of a rotarydiaphragm pump according to the present invention, background partsbeing omitted for clarity in the drawing.

FIG. 6D is a side view of the articulating mechanism of a rotarydiaphragm pump according to the present invention, shown from adirection rotated 90° from the orientation of FIG. 6C and withbackground parts being omitted for clarity in the drawing.

Similar reference characters denote corresponding features consistentlythroughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The rotary diaphragm pump has a case defining a plurality of chamberssurrounding an elliptical core or cavity. A corresponding ellipticalframe and diaphragm assembly is disposed within the case. The diaphragmis in the form of a closed band that forms an elliptical shape whenstretched over its frame. A mechanism urges the band outward into thechambers to provide pumping action in each of the chambers. Theresulting multiple strokes or pulses in each revolution of the mechanismprovide a relatively smooth flow from the pump, while the ellipticalband configuration of the diaphragm results in relatively low stresseson the diaphragm.

FIGS. 1 and 2 of the drawings show a first embodiment of the rotarydiaphragm pump 10, illustrating its basic components. The pump 10 has acase 12 having four chambers 14 a, 14 b, 14 c, and 14 d (definedcounterclockwise from the upper left chamber 14 a) surrounding anelliptical central cavity or core 16. The case 12 has mutually opposedfirst and second ends 18 and 20 having elliptical openings therethrough.An elliptical diaphragm frame 22 is installed in the elliptical cavity16. The diaphragm frame 22 is formed by two elliptical hoops joined byspaced apart posts, leaving large gaps between the posts. A flexible,resilient, band-shaped diaphragm 24 is stretched over the exterior ofthe frame 22 prior to installation of the frame in the case 12. Theframe 22 and the diaphragm 24 have substantially the same width as theaxial thickness of the case 12. The diaphragm 24 separates the fourchambers 14 a through 14 d from the elliptical cavity 16 in the centerof the case 12. First and second end plates 26 and 28 attach to therespective ends 14 and 16 of the case 12. The first end plate 26 has acentral passage or aperture 30 for the passage of a drive shaft 32therethrough.

A diaphragm drive assembly or actuator assembly 34, comprising anarticulating pantograph of generally rhomboid configuration, is alsoinstalled within the elliptical cavity 16 of the case 12. The diaphragmactuator 34 is shown in detail in FIGS. 2, 4A through 46, and 5A through5E and FIGS. 6A-6D. The diaphragm actuator 34 is built upon a four-barlinkage assembly. Each of the four bars is a link 39 having theconfiguration shown in FIG. 6A. The link 39 has a cylindrical hub 39 chaving a first arm or leaf 39 a extending radially outward from one endof the hub 39 c, and a second arm of leaf 39 b extending radiallyoutward 180° opposite the first arm 39 a from the opposite axial end ofthe hub 39 c. The hub 39 c has a bore extending through the hub 39 caxially, and the end of each arm 39 a, 39 b has an aperture 39 e definedtherein.

As shown in FIGS. 2, 6C and 6D, the links 39 are assembled in a four-barloop with the end of the first arm 39 a of one link aligned with the endof the second arm 39 b at each of the four corners of the loop, the endsbeing joined by pivot pins 43. One pair of diagonally opposite cornersof the four-bar linkage has a piston roller 42 rotatably mounted on thepivot pin between the ends of the link arms 39 a, 39 b. The other pairof diagonally opposite corners of the four-bar linkage has a pair oftrack wheels or cam rollers 40 rotatably mounted on the ends of thepivot pins 43, which extend outward from the ends of the link arms 39 a,39 b (in some embodiments, the actuator has only a single track wheel 40mounted on the pivot pins 43 and the diaphragm frame 22 has only asingle track 44 a or 44 b). As shown in FIGS. 2 and 6D, a pair ofparallel crank bars 36 extend between one pair of opposing hubs 39 c onopposite sides of the four-bar linkage. The two crank bars are connectedat their ends by pivot pins that extend through the hubs 39 c. Thecenter of the crank bars 36 defines a keyway. A keyed drive shaft 32extends through the keyways in the crank bars 36.

An alternative embodiment of the links is shown in FIG. 6B. In thisembodiment, the cylindrical hub 39 c has been replaced by a rectangularbox hub 41 c. However, this link also has oppositely extending leafs orarms 41 a, 41 b that are offset from each other by the length of the hub41 c, a bore 41 d extending axially through the hub 41 c, and apertures41 e defined in the ends of the arms 41 a, 41 b, so that the link 41functions in the same manner as the link 39.

The inner surfaces of the axially opposed ends of the diaphragm frame 22serve as first and second elliptical tracks 44 a and 44 b. The guidewheels 40 roll along either or both of these two tracks 44 a, 44 bdepending upon whether two guide wheels 40 are installed upon each pivotaxle of the links 59, as noted further above. In addition, each of theend plates 26 and 28 includes an elliptical guide 46 a, 46 b protrudinginto the elliptical cavity. The guide wheels 40 are thus capturedbetween their respective tracks 44 a and/or 44 b of the diaphragm frame22 and the corresponding elliptical guides 46 a and 46 b of the firstand second end plates 26 and 28. Accordingly, the guide wheels 40articulate inward and outward according to their positions along theelliptical tracks 44 a, 44 b and guides 46 a, 46 b, retracting inward asthey approach the minor axis of the ellipse and extending outward asthey approach the major axis of the ellipse.

The above-described operation of the rhomboid pantograph mechanism ofthe diaphragm actuator 34 results in the two piston rollers 42 moving ina direction directly opposite that of the wheels 40, i.e., the rollers42 move outward as the wheels 40 move inward, with the rollers 42 movinginward as the wheels 40 move outward. FIGS. 4A through 4G illustrate theprogressive articulation of the diaphragm actuator 34 as it rotatescounterclockwise through 90° of rotation. In FIG. 4A, the two wheels 40illustrated are essentially at their maximum extension along the majoraxis of the elliptical diaphragm frame 22 and the two piston rollers 42are retracted along the minor axis of the diaphragm frame 22, i.e., attheir closest approach to one another, providing maximum clearancebetween the two rollers 42 and the diaphragm 24.

In FIG. 4B, the upper wheel 40 has rotated counterclockwise toward thefirst chamber 14 a, and the corresponding opposite lower wheel 40 hasrotated counterclockwise toward the third chamber 14 c. The distancebetween the two wheels 40 must decrease, as the wheels are travelingfrom the longer major axis of the elliptical track 44 b toward theshorter minor axis of the track. Accordingly, the linkage of thepantograph mechanism of the diaphragm actuator 34 causes the two pistonrollers 42 to begin to move away from one another, so that the tworollers 42 just begin to contact the diaphragm 24 in FIG. 4B.

FIG. 4C illustrates the configuration and orientation of the diaphragmactuator 34 after about 30° of counterclockwise rotation. The two camrollers or track wheels 40 are at their approximate medial positionsrelative to their maximum and minimum extension, so that the diaphragmactuator is very close to a square configuration. The two piston rollers42 have correspondingly moved outward, where they are distending thediaphragm 24 into the two chambers 14 b and 14 d to reduce their volume.It will be seen that this results in any fluid within the chambers 14 band 14 d being expelled from those chambers via their outlet ports(discussed further below).

The two track wheels 40 are shown rotated about 45° degreescounterclockwise in FIG. 4D, so that the span between the wheels 40decreases further as the wheels 40 approach the minor axis of the guidetrack 44 b of the diaphragm frame 22. The two piston rollers 42 havecorrespondingly spread farther apart from one another, distending thediaphragm band 24 farther into the two chambers 14 b and 14 d to expelfluid from those two chambers.

FIG. 4E shows the orientation and configuration of the articulatingdiaphragm actuator 34 as the track wheels 40 have rotated about 60°counterclockwise from the positions shown in FIG. 4A. The span betweenthe two guide wheels 40 continues to decrease as they approach the minoraxis of the elliptical diaphragm frame 22, and the two piston rollers 42extend away from one another correspondingly to distend the diaphragmband 24 into the two chambers 14 b and 14 d.

In FIG. 4F, the diaphragm actuator 34 has rotated about 75° degrees fromits initial orientation, so that the track wheels 40 are nearly at theirclosest approach to one another due to the smaller span of the minoraxis of the diaphragm frame 22 and its track 44 b. The piston rollers 42have correspondingly extended away from one another to nearly theirmaximum span. The two rollers 42 are accordingly approaching the majoraxis of the elliptical diaphragm frame 22. However, the span along themajor axis of the diaphragm frame is slightly greater than the maximumspan between the two diaphragm rollers 42. Thus, the two rollers 42 aredistending the diaphragm 24 to a lesser degree than previously in therotational cycle, even though the rollers 42 are still moving slightlyfarther away from one another at this position.

Finally, in FIG. 4G the track wheels 40 have rotated 90° from thestarting position shown in FIG. 4A, i.e., they are oriented along theminor axis of the elliptical diaphragm frame 22 and are at their minimumspan between one another. Accordingly, the two piston rollers 42 are attheir maximum distance from one another, aligned along the major axis ofthe diaphragm frame 22. As noted above, the major axis of the diaphragmframe 22 is somewhat greater than the maximum span between the twopiston rollers 42, thus allowing the rollers 22 to clear the interiorends of the case 12 as the diaphragm actuator 34 rotates within the case12.

Further rotation of the diaphragm actuator through another 90° ofrotation results in the two guide wheels 40 expanding away from oneanother as they travel toward the major axis of the diaphragm frame 22,so that the two piston rollers 42 correspondingly retract toward oneanother. However, it will be seen that the piston rollers 42 will extendbeyond the elliptical shape of the diaphragm 24, just as they didthrough much of the first 90° of rotation of the diaphragm actuator 34.Thus, the rollers 42 will distend the portions of the diaphragm 24across the first and third chambers 14 a and 14 c through the secondquadrant of rotation, pumping fluid from those two chambers 14 a, 14 cwhile fluid is drawn into the other two chambers 14 b and 14 d. When thediaphragm actuator 34 has rotated through 180° of rotation, the cyclecontinues in the pattern shown in FIGS. 4A through 4G, but with the twotrack wheels 40 and the two piston rollers 42 reversed in theirpositions in the case 12. The pump operation continues as described. Therotary diaphragm pump 10 produces eight pump strokes per revolution ofthe diaphragm actuator 34 due to the four chambers 14 a through 14 d andthe two piston rollers 42. While FIGS. 4A through 4G illustrate theoperation of the rotary diaphragm pump 10 in counterclockwise rotation,it will be seen that the pump 10 is equally capable of rotating in theopposite clockwise direction with no structural changes. Such reversedrotation results in reversal of the direction of the flow of fluid movedthrough the pump 10.

FIG. 3 is a schematic geometric diagram showing the shapes of thechambers 14 a through 14 d superimposed over the elliptical outline ofthe central cavity 16 of the device. The curve generating the outline ofthe chambers 14 a-14 d is developed by constructing a right trianglehaving its right angle at the center or origin O of the ellipticalcavity 16, having a first leg defined as the distance between the originO and a point along the periphery of the elliptical cavity and a secondleg defined as the distance between the origin O and a point along theperiphery of the chambers 14 a through 14 d. The hypotenuse of thetriangle is a constant length. Only the length of the other two legsvaries according to the locations of their end points along therespective peripheries of the elliptical cavity 16 and the chambers 14 athrough 14 d. The triangle is then rotated about the origin O so thatthe distal end of the second leg generates a continuous series of pointsdefining the chambers 14 a through 14 d. The result is a shape somewhatresembling the Arabic numeral 8.

It will be seen that the curve of the outline of the chambers 14 a-14 dwill vary according to the eccentricity e of the elliptical cavity 16,which is defined according to the equation e=√{square root over(1−(b/a)²)}, where b is the minor axis of the ellipse and a is the majoraxis of the ellipse. Thus, the width of the narrowed central span of thechambers 14 a-14 d will decrease as the eccentricity e of the ellipseincreases, i.e., the minor axis b of the ellipse becomes a smallerfraction of the major axis a. It will be seen that the width of thenarrowed central span of the four chambers 14 a through 14 d willapproach zero as the eccentricity e of the ellipse approaches infinity.The opposite extreme is found when the ellipse has an eccentricity e ofzero, i.e., it is a circle. In this case all three of the legs of thetriangle will remain of constant length as the triangle is rotated aboutthe origin, i.e., the result will be another circle.

In the example of FIG. 3, a first leg r₁ of the first triangle extendsfrom the origin O at an angle θ₁ from the minor axis b of the ellipse toa point P₁ on the periphery of the ellipse 16. A first leg r₂ of thesecond triangle extends from the origin O at an angle θ₂ from the minoraxis a. The lengths of the legs r₁ and r₂ vary according to the anglesθ₁ and θ₂ from the minor axis a due to the elliptical shape to whichthey extend. The opposite legs R₁ and R₂ extending from the origin O topoints C₁ and C₂ on the periphery of the chambers 14 a through 14 d willalso vary in length. However, the lengths L of the hypotenuses of bothof these triangles are equal to one another, i.e., the length L isfixed. Thus, as the triangles are defined by their right angles betweentheir two legs r₁, R₁ and r₂, R₂ and the lengths L of their hypotenusesare equal to one another, the points C₁ and C₂ will be definedaccordingly. The locations of the points C₁, C₂, etc. are determinedaccording to the equation R=√{square root over (L²−r²)} where R is theradial distance from the center of the elliptical cavity to theperiphery of the chambers, L is the fixed length hypotenuse of a righttriangle having its right angle at the center of the elliptical cavity,and r is the length of the leg of the right triangle extending from thecenter of the elliptical cavity to a point along the periphery of theelliptical cavity. It will be seen that the procedure described hereinfor generating these two points C₁ and C₂ may be expanded to generate alarge number of such points, thereby defining the periphery of the fourchambers 14 a through 14 d. Allowance is made for the radii of the trackwheels 40 and the piston rollers 42 of the diaphragm actuator 34 toarrive at the final shape.

The rotary diaphragm pump lends itself to several output configurations,depending upon the interconnections (or lack thereof) between thevarious inlet and outlet ports of the device. The case 12 includes fourinlet ports 48 a through 48 d, respectively, for the four chambers 14 athrough 14 d, and four outlet ports 50 a through 50 d for the chambers14 a through 14 d. These various inlet and outlet ports may be connectedwith one another using interconnecting passages and correspondingone-way check valves to provide a number of different pumpconfigurations, as shown in FIGS. 5A through 5E.

The basic configuration illustrated in FIG. 5A does not include anypassages interconnecting any of the various chambers of the pump. Inthis configuration each of the chambers 14 a through 14 d comprises asingle isolated pump, so that the rotary diaphragm pump 10 of FIG. 5Aprovides four single stage pumps. Each of the chambers and pumps may beconnected to different inlets and outlets from one another and mayoperate independently (except for the common drive for the articulatingdiaphragm actuator 34) to transfer different fluids to and fromdifferent sources.

The rotary diaphragm pump 110 of FIG. 5B is identical to the pump 10 ofFIGS. 1, 2, and 4A through 4G, with the exception of its externalinterconnecting passages. The pump 110 includes a first interconnectingpassage 52 extending between the outlet port 50 a of the first chamber14 a and the inlet port 48 b of the second chamber 14 b, and an oppositesecond interconnecting passage 54 extending between the outlet port 50 cof the third chamber 14 c and the inlet port 48 d of the fourth chamber14 d. The interconnection of the first and second chambers 14 a and 14 bresults in a two-stage pump. Fluid enters the first chamber 14 a throughthe first inlet port 48 a and is pumped from the first chamber 14 a intothe second chamber 14 b, and thence pumped from the second chamber 14 b,where the fluid exits from the second chamber outlet port 50 b.Similarly, the third chamber 14 c pumps fluid into the fourth chamber 14d from the third inlet port 48 c by means of the second interconnectingpassage 54. The third and fourth chambers 14 c and 14 d comprise asecond two-stage pump with fluid exiting from the fourth outlet port 50d. Each of the interconnecting passages 52 and 54 includes a one-waycheck valve 58 therein to prevent return of fluid from the secondarychamber back to the primary chamber. It will be seen that the directionof operation of the pump 110 (and other pumps incorporating variousinterconnecting passages) may be reversed easily by reversing theorientation of the check valve(s) 58 and reversing the direction ofrotation of the drive mechanism.

The rotary diaphragm pump 210 of FIG. 5C is also configured similar tothe pumps 10 of FIGS. 1, 2, and 4A through 4G, as well as being similarto the pump 110 of FIG. 5A. The exception is the single interconnectingpassage 54 between the third and fourth chambers 14 c and 14 d in thepump configuration 210 of FIG. 5C. The pump 210 of FIG. 5C includes twosingle-stage pumps and a two-stage pump. The first single-stage pumpcomprises the first chamber 14 a, which draws fluid in through its inletport 48 a and expels that fluid from its outlet port 50 a. The secondsingle-stage pump is independent of the first single-stage pump (exceptfor their common drive), and draws fluid in through its inlet port 48 band expels the fluid from its outlet port 50 b. The two-stage pumpcomprises the third and fourth chambers 14 c and 14 d. Fluid is drawn inthrough the inlet port 48 c of the third chamber 14 c, passes throughthe interconnecting passage 54 between the outlet port 50 c of the thirdchamber 14 c and the inlet port 48 d of the fourth chamber 14 d, and isthen expelled from the outlet port 50 d of the fourth chamber 14 d.

The rotary diaphragm pump 310 of FIG. 5D is also configured similar tothe pumps 10 of FIGS. 1, 2, and 4A through 4G, the pump 110 of FIG. 5A,and the pump 210 of FIG. 5B. However, the pump 310 of FIG. 5D includesonly one single-stage pump and a three-stage pump. The single-stage pumpcomprises the second chamber 14 b, which draws fluid in through itsinlet port 48 b and expels that fluid from its outlet port 50 b. Thethree-stage pump comprises the third, fourth, and first chambers 14 cand 14 d, in which fluid is drawn in through the inlet port 48 c of thethird chamber 14 c, passes through the interconnecting passage 54between the outlet port 50 c of the third chamber 14 c and the inletport 48 d of the fourth chamber 14 d, continues through the thirdinterconnecting passage 56 from the outlet port 50 d of the fourthchamber 14 d to the inlet port 48 a of the first chamber 14 a, and isthen expelled from the outlet port 50 a of the first chamber 14 a.

The rotary diaphragm pump 410 of FIG. 5E is also configured similar tothe other pumps discussed further above. However, the pump 410 of FIG.5E comprises only one four-stage pump. The four-stage pump 410 drawsfluid in through the inlet port 48 c of the third chamber 14 c, passesthe fluid through the interconnecting passage 54 between the outlet port50 c of the third chamber 14 c and the inlet port 48 d of the fourthchamber 14 d, the fluid continuing through the third interconnectingpassage 56 from the outlet port 50 d of the fourth chamber 14 d to theinlet port 48 a of the first chamber 14 a, whereupon the first chamber14 a pumps the fluid from its outlet port 50 a through theinterconnecting passage 52 to the inlet port 48 b of the second chamber14 b, the fluid being expelled from the outlet port 50 b of the secondchamber 14 b. This configuration has the potential to increase thepressure of the delivered fluid at the outlet port 50 b to asignificantly higher level than that provided by a lesser number of pumpstages.

It will be seen that the arrangements of the various interconnectingpassages 52, 54, and 56 are exemplary, and that they may be rearrangedbetween any of the inlet ports and outlet ports as desired to achieve adesired pump configuration. The direction of operation of any of thepump configurations is easily accomplished by reversing the orientationof the check valve(s) in their interconnecting passages and reversingthe direction of rotation of the drive, as noted further above.Moreover, it is possible to join two or more cases together in tandem toincrease the output of the pump assembly. A two-case pump configurationis indicated in FIG. 2 of the drawings, with the second case 12 a beingshown in broken lines in FIG. 2. The two cases 12 and 12 a would includean intermediate plate 27 therebetween, the intermediate plate 27 havingtwo mutually opposed elliptical guides (as shown on the second end plate28 in FIG. 1) disposed upon its oppositely facing surfaces and adriveshaft passage disposed therethrough in the manner of the first endplate 26. It will be seen that any number of cases may be joinedtogether in tandem, each adjacent pair of cases having an intermediateplate disposed therebetween. The various diaphragm actuators in such amultiple case pump may be rotationally staggered relative to one anotherto produce an even smoother output from the multiple chambers of such apump.

It is to be understood that the present invention is not limited to theembodiments described above, but encompasses any and all embodimentswithin the scope of the following claims.

I claim:
 1. A rotary diaphragm pump, comprising: at least one casehaving a first end, a second end opposite the first end, and a pluralityof chambers surrounding an elliptical cavity; a first end plate disposedupon the first end of the case; a second end plate disposed upon thesecond end of the case; an elliptical diaphragm frame disposed withinthe elliptical cavity of the case; a flexible, resilient diaphragmhaving the form of a closed band, the diaphragm being disposed about thediaphragm frame, the diaphragm sealing each of the chambers from oneanother and from the elliptical cavity; and a rotary mechanism disposedwithin the elliptical cavity of the case, the mechanism selectivelyrotating within the case and periodically distending the diaphragm intoeach of the chambers of the case, thereby producing a pumping action. 2.The rotary diaphragm pump according to claim 1, wherein: the diaphragmframe defines at least one elliptical track therein; and the rotarymechanism comprises an articulating pantograph having: a generallyrhomboid configuration; a plurality of track wheels disposed upon thepantograph mechanism, the wheels traveling along the at least oneelliptical track of the diaphragm frame; and a plurality of pistonrollers disposed upon the pantograph mechanism, the rollers periodicallydistending the diaphragm into each of the chambers of the case, therebyproducing the pumping action.
 3. The rotary diaphragm pump according toclaim 1, wherein the elliptical cavity has a center, a minor axis, and aperiphery, the chambers having a periphery defined by the equationR=√{square root over (L²−r²)} where R is the radial distance from thecenter of the elliptical cavity to the periphery of the chambers, L isthe fixed length hypotenuse of a right triangle having its right angleat the center of the elliptical cavity, and r is the length of the legof the right triangle extending from the center of the elliptical cavityto a point along the periphery of the elliptical cavity.
 4. The rotarydiaphragm pump according to claim 1, wherein: the plurality of chamberscomprises four chambers; and each of the chambers includes an inlet portand an outlet port.
 5. The rotary diaphragm pump according to claim 4,further comprising: an interconnecting passage extending between theinlet port of at least one of the chambers and the outlet port ofanother one of the chambers; and a one-way check valve disposed in theinterconnecting passage.
 6. The rotary diaphragm pump according to claim1, further comprising an elliptical guide protruding inward from eachsaid end plate.
 7. The rotary diaphragm pump according to claim 1,wherein said at least one case comprises a plurality of cases joined toone another in tandem, the rotary diaphragm pump further comprising anintermediate end plate disposed between each of the cases.
 8. A rotarydiaphragm pump, comprising: at least one case having a first end, asecond end opposite the first end, and a plurality of chamberssurrounding an elliptical cavity, each of the chambers having a fluidinput port and a fluid output port; a first end plate disposed upon thefirst end of the case; a second end plate disposed upon the second endof the case; an elliptical diaphragm frame disposed within theelliptical cavity of the case, the diaphragm frame defining at least oneelliptical track; a flexible, resilient diaphragm, the diaphragm beingan endless loop disposed about the diaphragm frame, the diaphragmsealing each of the chambers from one another and from the ellipticalcavity; a diaphragm actuator having: four elongate links; four pivotpins connecting the ends of the four elongate links to form a four-barlinkage having a rhomboid configuration; piston rollers rotatablymounted on two of pivot pins diagonally opposite each other; trackwheels rotatably mounted on the other two diagonally opposite pivotpins; and a pair of elongate crank bars pivotally attached to oneparallel pair of the links at a midpoint of the elongate links onopposite sides of the four bar linkage, the crank bars having a keywaydefined at a midpoint of the elongate crank bars, the diaphragm actuatorbeing disposed in the elliptical cavity with the track wheels rotatingon the diaphragm frame track and the piston rollers being extendiblethrough the diaphragm frame to bear against the diaphragm; and a keyeddrive shaft inserted through the keyholes in the crank bars; whereinselective rotation of the drive shaft causes the piston rollers to pushthe resilient diaphragm into diagonally opposite chambers in the case,followed by retraction of the piston rollers and diaphragm from thechambers to pump fluid through the input and output ports of thechambers.
 9. The rotary diaphragm pump according to claim 8, whereinsaid at least one elliptical track comprises parallel first and secondelliptical tracks defined by the diaphragm frame.
 10. The rotarydiaphragm pump according to claim 8, wherein the elliptical cavity has acenter, a minor axis, and a periphery, the chambers having a peripherydefined by the equation R=√{square root over (L²−r²)} where R is theradial distance from the center of the elliptical cavity to theperiphery of the chambers, L is the fixed length hypotenuse of a righttriangle having its right angle at the center of the elliptical cavity,and r is the length of the leg of the right triangle extending from thecenter of the elliptical cavity to a point along the periphery of theelliptical cavity.
 11. The rotary diaphragm pump according to claim 8,wherein the plurality of chambers comprises four chambers.
 12. Therotary diaphragm pump according to claim 11, further comprising: aninterconnecting passage extending between the inlet port of at least oneof the chambers and the outlet port of another one of the chambers; anda one-way check valve disposed in the interconnecting passage.
 13. Therotary diaphragm pump according to claim 8, further comprising anelliptical guide protruding inwardly from each end plate, the trackwheels rolling between the elliptical guides and the tracks defined bythe diaphragm frame.
 14. The rotary diaphragm pump according to claim 8,wherein said at least one case comprises a plurality of cases joined toone another in tandem, the rotary diaphragm pump further comprising anintermediate end plate disposed between each of the cases.
 15. A rotarydiaphragm pump, comprising: at least one case having a first end, asecond end opposite the first end, and a plurality of chamberssurrounding an elliptical cavity, the elliptical cavity having a center,a minor axis, and a periphery, the chambers having a periphery definedby the equation R=√{square root over (L²−r²)} where R is the radialdistance from the center of the elliptical cavity to the periphery ofthe chambers, L is the fixed length hypotenuse of a right trianglehaving its right angle at the center of the elliptical cavity, and r isthe length of the leg of the right triangle extending from the center ofthe elliptical cavity to a point along the periphery of the ellipticalcavity; a first end plate disposed upon the first end of the case; asecond end plate disposed upon the second end of the case; an ellipticaldiaphragm frame disposed within the elliptical cavity of the case, thediaphragm frame defining at least one elliptical track; a flexible,resilient diaphragm, the diaphragm being an endless loop disposed aboutthe diaphragm frame, the diaphragm sealing each of the chambers from oneanother and from the elliptical cavity; a diaphragm actuator having:four elongate links; four pivot pins connecting the ends of the fourelongate links to form a four-bar linkage having a rhomboidconfiguration; piston rollers rotatably mounted on two of the pivot pinsdiagonally opposite each other; track wheels rotatably mounted on theother two diagonally opposite pivot pins; and a pair of elongate crankbars pivotally attached to one parallel pair of the links at a midpointof the elongate links on opposite sides of the four bar linkage, thecrank bars having a keyway defined at a midpoint of the elongate crankbars, the diaphragm actuator being disposed in the elliptical cavitywith the track wheels rotating on the diaphragm frame track and thepiston rollers being extendible through the diaphragm frame to bearagainst the diaphragm; and a keyed drive shaft inserted through thekeyholes in the crank bars; wherein selective rotation of the driveshaft causes the piston rollers to push the resilient diaphragm intodiagonally opposite chambers in the case, followed by retraction of thepiston rollers and diaphragm from the chambers to pump fluid through theinto and out of the chambers.
 16. The rotary diaphragm pump according toclaim 15, wherein: the plurality of chambers comprises four chambers;and each of the chambers includes an inlet port and an outlet port. 17.The rotary diaphragm pump according to claim 16, further comprising: aninterconnecting passage extending between the inlet port of at least oneof the chambers and the outlet port of another one of the chambers; anda one-way check valve disposed in the interconnecting passage.
 18. Therotary diaphragm pump according to claim 15, wherein said at least onecase comprises a plurality of cases joined to one another in tandem, therotary diaphragm pump further comprising an intermediate end platedisposed between each of the cases.